Coustrtjctioet of bridges



UNE

A. BRADWAY AND E. VALENTINE, OF MONSON, MASSACHUSETTS.

CONSTRUCTION OF BRIDGES.

To all whom it may concern:

Be it known that we, ABEL BRADWAY and ELIJAH VALENTINE, of Monson, in the county of Hampden and State of Massachusetts, have invented a new and Improved Bridge; and we do hereby declare that the following is a full and eXact description thereof, reference being had to the accompanying drawings, making part of this specification, in which- Figure 1, is a plan of one side of our improved bridge, Fig. 2, a side elevation of the same, Fig. 3, a transverse vertical section, in the line of Fig. 1, Fig. 4, a transverse vertical section in the line y-Q of Fig. 1, and Fig. 5, perspective of a part detached. j

LikeA letters designate similar parts in all the figures.

Having laid the cross-joists E, E, &c., the string-pieces C, C, &c., are placed. upon said cross-joists in their proper positions. The posts F, F, &c., are then prepared with suitable grooves g, g, on each side and placed, without uniting thereto, upon the string-pieces C, C, &c., directly over the cross-joists E, E, &c. The diagonal braces b, b, &c., are then inserted between said posts, their ends fitting in the grooves g, ,g of the posts. Said braces are so arranged that each shall reach from the bottom of one post to the top of the next post and the ends of two adjacent braces shall be opposite to one another, and alternately at the bottom and top of a post. The upper string pieces B, B, are then laid, without uniting thereto, upon said posts and braces. We usually construct the string-pieces B, B, and C, C, of several layers of plank, or plates of the material employed, and unite Y them so as to break joints with one another.

The joints of the layers should always be directly under, or over, the posts F, F. The saddle-blocks A, A, &c., are next placed upon the string-pieces B, B, each one directly over a post F. The ties a a &c., are then inserted up through the cross-joists E, E, and the saddle-blocks A, A, and secured rmly by nuts and screws. Finally, tension braces c, c, &c., are inserted, one end of each through a saddle-block, and, after passing under the cross-joist situated directly below the next saddle-block, passes up through the next saddle-block beyond. Both ends of each tension-brace are then tightly drawn up and secured by nuts and screws. The next tension-brace commences with the next saddle-block in order, and so on through the whole number. The whole bridge is thus tied firmly by these tension-braces crossing one another and drawing in. opposition to one another. A firm and strong bridge is thereby formed wit-h little comparative cost, and of very simple construction. But the chief advantage consists in constructing it without tenons and mortises, so that the several parts, and especially the stringpieces B, B, and C, C, may slide upon the other parts sufiiciently to adapt themselves to the contract-ion and expansion of material consequent on the changes in the temperatureof t-he atmosphere, while at the same time, the bridge is not weakened by cutting tenons and mortises, and it, in other respects, fully as strong and durable as when constructed in any other way known to us. Thus, the string-pieces B, B, and C, C, may be driven endwise through the bridge although the screws of the tension-braces and ties may be so firmly secured as to render the bridge perfectly rigid and campact.

By Athis our improved construction, a bridge of any practicable span may be built of iron, without being liable to be destroyed or injured by its great contraction and expansion under the influence of changes of temperature, which result, has never, to our knowledge, been accomplished before; and in consequence of the hitherto unavoidable inconvenience resulting from that property of the metal, iron bridges of limited span only have heretofore been successfully erected.

Vhat we claim as our invention and desire to secure by Letters Patent, is-

The combination of the string pieces with the posts F, F, the cross-joists E, E, the saddles A, A, the diagonal braces o, Z), and the ties a, a, of a bridge frame in such manner that the said string pieces are enabled to move longitudinally under the influence of variations of temperature-or other cause-without injury to themselves or to the parts with which they are combined, substantially as herein set forth.

The above specification of our invention signed and witnessed this first day of May, 1852.

ABEL BRADWAY. ELIJAH VALENTINE.

Witnesses:

J. A. HALL, LEWIS MERRIGK. 

